For undirected graphs, however, only three conditional lower bounds are known: the \(m^{2-o(1)}\)  [1]} lower bound for \((3/2-\varepsilon )\) -approximation, the \(m^{3/2-o(1)}\)  [2]} lower bound for \((5/3-\varepsilon )\) -approximation, and the \(m^{4/3-o(1)}\)  [3]} lower bound for \((7/4-\varepsilon )\) -approximation (see Figure REF ).
